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Childhood is the most sensitive period for neurodevelopment, but unfortunately it can be disrupted in many ways – from abuse or neglect to exposure to war and violence.
In 1966, Romania introduced extreme policies to increase the country’s birth rate.
This led to the widespread abandonment of children, who ended up in orphanages, in terrible conditions, where they received no care, attention or love.
Despite being tragic, this infamous “natural experiment” allowed us to draw some conclusions about the effects of early trauma on the brain.
A 2020 study in PubMedrevealed that many of these children had smaller brain volumeswhich partially explained his poor cognitive performance. This atrophy was more severe in children who spent more time in institutions.
A matter of stress
Understanding the neurobiological effects of childhood adversity can help scientists understand and treat its long-term psychological effects.
There is evidence that these particularly affect the main stress regulation system, known as the stress axis. hypothalamus-pituitary-adrenal.
The activity of this system can be measured through hormones such as cortisol, known collectively as glucocorticoids. In normal amounts, cortisol helps mobilize the body to face threats or challenges.
However, excessive amounts can be harmful. For example, the children exposed to war have high levels of cortisol and immunoglobulin A in saliva, which also indicates high activity of the immune system.
Changes in the brain
The marks of adversity on the brain may also be more localized. One of the areas most sensitive to the effects of stress is the hippocampusa crucial structure in the formation of memories and spatial orientation, among other functions.
This sensitivity is due to its high concentration of receptors glucocorticoids, the “stress hormones”which are present at levels high in families exposed to war.
The largest and most recent (2024) on the subject reported a 17% reduction in hippocampal size among children exposed to three or more traumatic events compared to those who experienced none.
The two types of trauma
It is important to note that adversity varies not only in terms of severity, but also in terms of type.
Os abuse or mistreatment lead to trauma commission; while the neglect or deprivation lead to trauma omission.
A 2019 systematic review of research concluded that the adversity created by commission – such as physical or sexual abuse or exposure to gender-based violence – affects limbic and paralimbic structures, including the amygdala and insular cortex.
These areas are part of the brain’s “alert system” and abuse causes them to be constantly hyperactive. This, in turn, causes extreme reactions to harmless stimulias occurs in post-traumatic stress disorder.
In contrast, neglect tends to affect the prefrontal areas of the brain, which are responsible for more complex processes such as planning and reasoning.
This last aspect was clearly observed in the aforementioned study on children taken in by the Romanian State, where the lack of care resulted in brain atrophy and cognitive deficits.
Different types of adversity can also affect development in opposite ways: one from 2018 concluded that neglect delays maturation, while mistreatment accelerates it.
And even genes change
One of the most impressive discoveries of this century is that circumstances and the environment can alter genetic mechanisms.
This happens through a process called epigeneticsaccording to which certain genes are expressed to a greater or lesser extent depending on the environment in which we live.
It has been discovered that maltreated children, for example, have genetic expression opposite to that expected (high expression of genes that normally have low activity, and vice versa).
Childhood abuse also causes “genetic aging”: a pattern of gene expression that is more advanced than normal for a person’s age. This aging is also associated with a higher risk of depressive symptoms.
Another surprising discovery is that some epigenetic changes can occur during embryonic development.
Another, about the tragic Dutch famine of 1944, revealed that people whose mothers had suffered hunger during early pregnancy showed changes in the expression of genes related to metabolism.
This partly explains their high body mass and blood triglyceride levels, compared to their siblings who were luckier and did not suffer from hunger during pregnancy.
The neurobiology of resilience
It is important not to be defeatist: the brain is highly malleable and many individuals can overcome early adversity. In psychology, this process is called resilience.
In one of the groups of adopted Romanian children, it was observed that IQ deficits decreased over the years after fostering, until they approached normal levels. Furthermore, children who were in these institutions for less than six months presented, from the beginning, normative values for all the variables studied.
Resilience research is just beginning to reveal the neurobiological and psychosocial factors that mitigate the impact of stress severe and chronic. In some people, this may even allow what is called post-traumatic growth.
